To investigate the community structure and diversity characteristics of bacteria and fungi in bulk spices marketed in Yunnan Region.

The 30 samples of bulk spices covering 6 categories, namely,star anise, chili pepper, white pepper, Amomum tsao-ko, Sichuan pepper and cumin, were collected from Yunnan Region. Using whole-genome sequencing, the diversity of bacteria and fungi was analyzed, and the microbial community structures of bacteria and fungi were investigated at the phylum and genus levels.

The dominant bacterial communities of the 6 spices at the phylum level were Proteobacteria, Firmicutes, Bacteroidota,Actinobacteriota, and white pepper samples had high diversity in bacterial community. At the genus level, the dominant bacterial community was Delftia. The dominant groups of fungal communities of 6 spices at the phylum level were Ascomycota and Basidiomycota, and star anise samples had high diversity in fungal community. At the genus level, the dominant community of different spices were different. The main pathogenic bacterial contaminants in the spices were Bacillus cereus and Cronobacter spp., and there was varying degrees of mold contamination.

Spices have high diversity in bacterial and fungal communities, and the dominant communities of bacterial and fungal are more consistent at the phylum level in different spices, while they may be different at the genus level. The bacterial and fungal communities in the spices covered both human pathogenic and plant pathogenic genera.

To investigate the effects of the betA and betB genes on stress resistance and virulence of Cronobacter.

Using Cronobacter sakazakii as the experimental subject, this study emplored betA, betB,and betAB gene knockout and restoration strains to invesitage the effects of betA and betB on biofilm formation ability, stress resistance and cellular virulence of Cronobacter.

The biofilm formation ability of each strain was detected, and found that deletion of betA and betB led to a decrease of biofilm formation. It was speculated that betA and betB promote biofilm formation in Cronobacter by controlling betaine synthesis. The effects of different temperatures and pH on Cronobacter were examined using fluorescence microscopy and flow cytometry. The results showed that under high temperature and acidic conditions, the survival rates of all Cronobacter strains decreased.Specifically, survival rates at pH 7 and pH 9 were significantly higher than at pH 5 (P<0.05), and survival rates at 48 ℃ were significantly lower than at 25 ℃ and 37 ℃ (P<0.05). The assessment of Cronobacter virullence in cell infection revealed that bacterial infection was led to changes in the levels of tight junction proteins within cells, for the CS 34, ΔbetB, ΔbetAB, cpbetA, cpbetB and cpbetAB strains caused significantly greater damage to cells after drying treatment compared to before drying, resulting in a decrease in cell viability and leading to a significant decrease in tight junction-associated proteins (P<0.01). When the betA gene was deleted, desiccated Cronobacter did not cause a significant decrease in cell viability compared to non-desiccated bacteria.

This study finds that deletion of the betA and betB genes weakens the biofilm formation ability of Cronobacter and reduces its tolerance to acid and high temperature. It is also observed that when the betA gene is present, bacteria that survive under desiccated conditions tend to have stronger virulence and cause greater cellular damage.

To investigate the pesticide residue levels and exposure risks of Fragaria ananassa in Qingdao.

A total of 150 batches of fresh Fragaria ananassa from the production bases in Qingdao were randomly selected. Based on the results of visits and investigations, typical pesticides in the 150 batches of samples were tested, and dietary intake risk assessment of typical pesticide residues in Fragaria ananassa was conducted.

It was found that 17 kinds of pesticide residues were detected in 150 batches of Fragaria ananassa in Qingdao, and 10 kinds of pesticides were registered for use in Fragaria ananassa, accounting for 58.8% of the total number of pesticides detected. The 7 kinds of unregistered pesticides were detected in Fragaria ananassa, accounting for 41.2% of the total detected pesticides. The types and quantities of pesticides detected were fungicides>insecticides>acaricides, and plant growth regulators were not detected. In the 5 different harvest periods,the highest pesticide residue levels and the detection frequency were detected in Februry and March. The risk coefficients of the 17 kinds of detected pesticides were all less than 1.5, indicating that the detected pesticides were at a low risk. The dietary intake risk of the detected pesticide residues in fresh Fragaria ananassa was also relatively low. This suggested that the impact of the 17 kinds of detected pesticides on the safety of Fragaria ananassa was acceptable.

Through the monitoring of pesticide residues of Fragaria ananassa in Qingdao, it is found that the qualified rate of pesticide residues in Fragaria ananassa is relatively high, the quality and safety status of Fragaria ananassa is good and acceptable. However, judging from the monitoring data, the use of unregistered pesticides in Fragaria ananassa still occurs, so the supervision of the use of unregistered pesticides in Fragaria ananassa should be further strengthened.

To investigate the contamination status of Burkholderia gladioli pathovar cocovenenans in the Flammulina filiformis production chain, and evaluate its potential toxin-producing risk and actual toxin production situation.

A total of 110 samples collected from various links in the Flammulina filiformis production chain were subjected to the isolation, identification and toxin-producing gene detection of Burkholderia gladioli in accordance with the 2025 national manual for risk monitoring of food contaminants and hazardous factors.

The 2 strains of Burkholderia gladioli were isolated, with an overall detection rate of 1.82%. The results of toxin-producing gene detection showed that all isolated strains did not carry bon and lacked the ability to produce bongkrekic acid.

There is a risk of Burkholderia gladioli contamination in the Flammulina filiformis production chain. It is necessary to strengthen the whole-chain management system, and combine advanced detection technologies with prevention and control measures to promote the healthy and sustainable development of the Flammulina filiformis production industry chain.

To clarify the mechanism of the effects of cold plasma-sun drying process on pesticide residues during the drying process of Lycium ruthenicum Murr.

The 6 kinds of commonly used pesticides in Lycium ruthenicum Murr, namely acetamiprid, carbendazim, imidacloprid, pyridaben, fenpyroximate and zeta-cypermethrin, were selected as the research objects. The pesticide residues in each drying stage were determined by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and the dynamic changes of processing factors (PF) and degradation rates were systematically analyzed. The residue change mechanism was explored in combination with the physicochemical properties of pesticides and process parameters, and a dietary exposure risk assessment was conducted.

Each drying procedure exerted significantly different effects on pesticide residues. Water washing exhibited the best residue removal performance, with degradation rates of 34.88%–73.14% for acetamiprid, carbendazim, imidacloprid and pyridaben. Only fenpyroximate and etoxazole underwent degradation after cold plasma treatment. After the drying process, all target pesticides did not show degradation effects. The dietary exposure riskassessment showed that the acute risk rate and chronic risk rate of the 6 kinds of pesticides were 0.001%–0.233% and 0.001%–0.167 % respectively, both far below the safety critical values.

The study confirms that the combined drying process of Lycium ruthenicum Murr is safe for consumption and can provide theoretical basis and data support for pesticide residue control and process optimization in Lycium ruthenicum Murr processing.

To assess the applicability of the MicroFast® Staphylococcus aureus test strips method for microbiological testing of food products.

This study presented a comprehensive validation of the test chart method, followed the performance specifications set out in the International Organization for Standardization ISO 16140—2: 2016. The validation covered its inclusiveness, exclusiveness and consistency with the test results of the current national standards. The results of both methods were statistically analyzed using t-test and Bland-Altman.

All 30 Staphylococcus aureus target strains showed typical purple colony characteristics on MicroFast test slices; 3 of the 30 non-target strains had atypical blue colonies, and no colony growth was observed colony growth on 27 strains the test slices. After correlation analysis, the MicroFast® Staphylococcus aureus test piece method showed a significant positive correlation with the results of the second method of GB 4789.10—2016 Food safety national standard-Food microbiological test-Staphylococcus aureus test, with a correlation coefficient (r) value of more than 0.976. The suitability of the test slices was also evaluated for a variety of food types, and the calculated β-expected tolerance intervals were all within ±0.5 logarithmic range.

MicroFast® Staphylococcus aureus test pieces have good inclusiveness and exclusivity, consistency and equivalence with current national standard methods, and are suitable for the quantitative detection of Staphylococcus aureus in food.